Association between serum 25-hydroxyvitamin D levels and cognitive function among older adults in Tianjin, China: a cross-sectional community-based study.

OBJECTIVE: To explore the association between serum 25-hydroxyvitamin D (25-OH-D) levels and mild cognitive impairment (MCI) and further analyse the association between serum 25-OH-D levels and different dimensions of cognitive function. DESIGN: Cross-sectional study. SETTING: Tianjin, China. PARTICIPANTS: A total of 866 participants aged 65 and above were enrolled in this study. OUTCOME: MCI was diagnosed based on the revised Petersen diagnostic criteria. Cognitive function was assessed by the Wechsler Adult Intelligence Scale Revised in China. RESULTS: The prevalence of MCI was 12.0%. Higher serum 25-OH-D levels were significantly associated with lower odds of MCI, as well as with MCI across all subgroups (p<0.05). Serum 25-OH-D levels were significantly and positively associated with full intelligence quotient (FIQ), verbal intelligence quotient (VIQ), information, similarity and vocabulary (p<0.05). The associations between serum 25-OH-D levels and cognitive function did not significantly differ by age, gender or education level, with no statistical evidence of interactive effects. CONCLUSION: Higher serum 25-OH-D levels were significantly associated with lower odds of MCI. Furthermore, serum 25-OH-D levels were significantly and positively associated with different dimensions of cognitive function, specifically FIQ, VIQ, information, similarity and vocabulary. There was no statistically significant interaction observed between serum 25-OH-D levels and age, gender or education level.